In a world of changing climate and increasing fishing pressure, the extent to which ecosystems are controlled by top-down, bottom-up, or middle-out controls is fundamental.

Biogeochemists often view the system in terms of physics and nutrient availability whereas fisheries scientists and higher predator ecologists take a more top-down perspective. The need for a new generation of end-to-end ecosystem models has helped​ focus attention on these two radically different perspectives of how foodwebs work. From either viewpoint, zooplankton act as key intermediaries between primary production and commercially exploited fish, and in some instances, they themselves are now being fished.

In this session we welcome a variety of approaches that shed light on the main controls on zooplankton (e.g. experimental, time-series analysis, meta-analyses, molecular, modelling)​.

Examples of bottom-up forcing include stresses from temperature, oxygen, pH, and the quantity, quality, and/or size distribution of food. Top-down processes include mortality due to natural predators (e.g. carnivorous zooplankton, planktivorous fish, baleen whales) and human activities (e.g. fishing). ​​​These forcing functions act together and vary according to scale, but there is some controversy on their relative strengths or importance.

We particularly welcome integrative approaches that include more than two trophic levels, to synthesize the diversity of study approaches on this topic.​